In a variety of clinical settings, it is important to measure certain chemical characteristics of plasma from whole-blood samples. For example, it is commonly important to measure the analytes, extracellular hemoglobin, bilirubin, and lipid particles in plasma. These settings range from a routine visit of a patient to a physician's office, an emergency room, or monitoring of a hospitalized patient, for example. Numerous techniques and apparatus are commonly used for measuring chemical characteristics of body fluids in clinical settings. Measurement of an analyte in a body fluid sample may be accomplished by numerous methods one of which is by spectroscopic determination.
Some techniques for analyzing body fluid are complex and may involve numerous steps such as centrifugation to prepare a fluid sample for measurement. For example, techniques for measuring analyte content in the plasma portion of a blood sample may involve preliminary steps such as centrifugation of whole blood to separate blood cells from the plasma portion. These preliminary steps add time, complexity and cost to previously known techniques for measuring analyte content in a body fluid.